Nowadays, aircraft/spacecraft usually provide the possibility of storing data on the aircraft/spacecraft during flight. Data of this kind are used for evaluation and for root cause analysis, e.g. after an incident.
Flight data recorders, which store data during the flight, are usually used in aircraft/spacecraft for this purpose. Following an incident, the flight data recorders are located and recovered. Following recovery, the stored data can be extracted and analyzed.
In order to locate the flight data recorders, the flight data recorders conventionally comprise a locating aid, known as an underwater locator beacon, which emits an acoustic signal having a frequency of approximately 37.5 kHz, which signal can be located using sonar-based techniques. The detection range for an acoustic signal of this kind is 4000 m.
In order to improve the process of locating a flight data recorder of this kind, locating aids that emit an acoustic signal having a frequency of approximately 8.8 kHz can also be used in modern flight data recorders. The acoustic signals having a frequency of 8.8 kHz can be located over a distance of approximately 13 km.
A possible locating aid is disclosed e.g. in WO 2013 088 275 A1.
The particular locating aid and thus also the aircraft/spacecraft can be located and recovered during an incident at sea, for example using recovery ships, which attempt to detect and pinpoint the acoustic signal of the locating aids.